opt: back to auto scroll

app/components/chat.tsx

@@ -528,7 +528,7 @@ export function Chat(props: {
         className={styles["chat-body"]}
         ref={scrollRef}
         onScroll={(e) => onChatBodyScroll(e.currentTarget)}
-        onWheel={() => setAutoScroll(false)}
+        onWheel={(e) => setAutoScroll(hitBottom && e.deltaY > 0)}
         onTouchStart={() => {
           inputRef.current?.blur();
           setAutoScroll(false);